It is written:
“There were giants on the earth in those days, and also afterward, when the sons of God came in to the daughters of men and they bore children to them. Those were the mighty men who were of old, men of renown.” (Genesis 6:4)
The Bible teaches that the nephilim were all killed during the Global Flood, and the fallen angels who fathered them were cast into the lowest depths of Hades. If that is the case, then why does Moses record that the giants (nephilim) were in the land “afterward,” i..e, after the Flood?
There are other passages which talk about the return of the Nephilim after Noah’s flood. For example:
Numbers 13:33-There we saw the giants (the descendants of Anak came from the giants); and we were like grasshoppers in our own sight, and so we were in their sight.”
Deuteronomy 1:28-Where can we go up? Our brethren have discouraged our hearts, saying, “The people are greater and taller than we; the cities are great and fortified up to heaven; moreover we have seen the sons of the Anakim there.” ‘
Deuteronomy 2:11-They were also regarded as giants, like the Anakim, but the Moabites call them Emim.
Deuteronomy 2:20-(That was also regarded as a land of giants; giants formerly dwelt there. But the Ammonites call them Zamzummim,
Amos 2:9-Yet it was I who destroyed the Amorite before them, Whose height was like the height of the cedars, And he was as strong as the oaks; Yet I destroyed his fruit above And his roots beneath.
Some have suggested that perhaps there was another rebellion among the angels that is not recorded in Scripture, in which there was another bringing forth of giants through angels and humans.
While this is possible, there are other explanations.
First, the Bible suggests that through witchcraft and sorcery (and possibly technology), some in the ancient world were able to transform themselves into Nephilim. The Bible tells us:
Genesis 10:8-Cush begot Nimrod; he began to be a mighty one on the earth.
“Is this what was happening in Genesis 10 concerning Nimrod when “… he began [khaw-lal (a word study here is enlightening as the verb indicates the ‘beginning’ of profaning oneself or defiling oneself either sexually or ritually—exactly what some scholars believe the Watchers did to humans and animals in the lead up to Nephilim)] to be [become] a mighty [Gibbowr (of which we derive Gibborim / Nephilim)] one in the earth.”? This text could be read, “Nimrod began to become a Nephilim” or “a child of the Nephilim.” Is this a record of a mature human agreeing to be altered at the genetic level?; 2) The offspring of this genetic alteration was ‘resurrected’ dead Nephilim….The most enlightening, corresponding evidence of the assertion above, is found in the historical relationship between the Nephilim and the Rephaim, or spirits of dead Nephilim. Rephaimcarries with it the meaning ‘to heal’ or to be ‘healed’ as in a ‘resurrection’. In the Ras Shamra texts, the Rephaim are described as both human and divine beings who worshipped the Amorite god Ba’al, the ruler of the underworld, where the Rephaim served as his acolyte assembly of lesser gods, kings, heroes, and rulers. These beings were believed to have power to return from the dead through incarnation in bodily form as gods or ‘Nephilim’.” (Thomas R. Horn, Nephilim Stargates, 1977-1993 (Kindle Edition); Anomalos Publishing Gresham)
Perhaps through the sorcery of the ancient world, the Nephilim giants were brought back from the grave to possess the humans who conjured them, transforming their physical bodies into something akin to their previous bodies that had been killed in the Flood.
Another theory that has been proposed by Ken Johnson is worthy of careful consideration.
“Jubilees 10.1-12 informs us that after the flood evil spirits began afflicting many of Noah’s descendants. Noah prayed to God to bind all of the demons away from men. God bound nine-tenths of the demons, leaving only one-tenth to tempt and torment man. Revelation 9 tells that the other nine-tenths will be released during the Great Tribulation. If the angels are bound, and the Nephilim are disembodied spirits, where did the giants after the flood come from? A third rebellion? No. The story continues: Genesis tells us that after the flood Noah divided the planet among his three sons. Ham was given what we call Africa and Shem, the middle east. Canaan, Ham’s son, left his territory and ventured North along the Mediterranean Sea. Why did Canaan travel all the way up the cost to found Sidon, his first city, in an area he knew was not his territory, then quickly settle another city (Tyre)? The map at the right shows that those two locations are the closest he could get to mount an expedition to Mount Hermon. He wanted to find information about the pre-flood giants! And Canaan grew, and his father taught him writing, and he went to seek for himself a place where he might seize for himself a city. And he found a writing which former (generations) had carved on the rock, and he read what was thereon, and he transcribed it and sinned owing to it; for it contained the teaching of the Watchers in accordance with which they used to observe the omens of the sun and moon and stars in all the signs of heaven. And he wrote it down and said nothing regarding it; for he was afraid to speak to Noah about it lest he should be angry with him on account of it. Jubilees 8.1-5 After finding the writing containing the science of the Watchers, Canaan sought to create a race of warrior giants using the same type of genetic tampering which was done before the flood. This explains how the giants came to be, but with a few problems. Second Samuel 21: 20 describes giants with six fingers on each hand and six toes on each foot. Moses led the children of Israel into battle with Og, the king of Bashan, who being a true giant, stood at least twelve feet tall (Deuteronomy 3: 11). Bashan was anciently called the Land of the Giants. Og actually reigned from Mt. Hermon (Joshua 12: 4-5), the place where the angels descended. Even up to King David’s time, Goliath remained (1 Samuel 17: 4). He was one-quarter giant and three-quarters Philistine and reached only nine feet, nine inches tall. Another race of giants were the Anakim (Numbers 13: 21-33). Some of the Amorites were as tall as a cedar tree (Amos 2: 9), probably referring to the sons of Anak. Other giant races found in the Old Testament included the Emim (Deuteronomy 2: 9-11), and the Zamzummim (Deuteronomy 2: 20-21). The Anakim, Emim, and the Zamzaummim were all equally tall. The valley of Hinnom was anciently called the Valley of Giants (Joshua 15: 8; 18: 16). Joshua destroyed all the Anakim except for a giant that escaped to Gaza (Joshua 11: 21-22), the later home of Goliath. David’s men killed Goliath’s brother and one other son of the giant (2 Samuel 21: 20-21). In four hundred years time the giant out bred, so that Goliath and his brothers were only nine feet tall instead of thirteen feet tall. The Genesis 6 word for giants (Nephilim) occurs in only one other place: Numbers 13: 33. These same post-flood giants who are called Nephilim in Numbers, are referred to as Rephaim in Deuteronomy 2: 11 and Genesis 14: 5. These passages show that the post-flood giants were a special kind of Nephilim called Raphaim. This means they were not the procreation of another angelic rebellion, but a genetic tampering by man in a similar fashion as the angels did in the pre-flood world.” (Ken Johnson, Th.D., The Ancient Book Of Enoch, 182-184 (Kindle Edition)).
The fallen angels and demons continue their work in the world today.